soft switch - wordpress.com · pdf file history spc • early exchanges (strowger and...
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Fathur AB
Anin A
Afif A
Hari A
Gary A
Dhika AB
April AB
Mulya AB
Rizka B
Dion AB
Siska AB
Mirel AB
Hani AB
Airita AB
Yusuf AB
Pilsung AB
Taegyun A
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Stored Program Control
Course Number : TTH2A3
CLO : 3
Week : 8
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Media Gateway on NGN
• Media Gateway (MG)
– On Transport plane that connects different type of network – Trunk Gateway, connects packet-based network with trunk network from PSTN
or ISDN – Access Gateway, provides services to CPE – Residential Gateway, connects
packet-based network with analog network
• Signaling Gateway (SG)
– Transforming signaling format, ex. SIP SS7
• Media Gateway Controller (MGC)
– Control Media Gateway and Signaling Gateway
– aka. Soft Switch (call setup for multimedia communication, detect and manage events, and manage media gateway based on configuration)
– Use MGCP (MGC Protocol) from ITU-T or Megaco from IETF
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Layers in NGN
4
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Crossbar Switch
• Electro-mechanical switch by using relay contact
• Numbers are stored in register to establish a call by activating several relay. This activation is done by marker
• Marker will become SPC (Stored Program Control)
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Unit Interface for Digital SPC
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What is SPC?
SPC (Stored program control) is:
• a telecommunications technology used for telephone exchanges
• controlled by a computer program stored in the memory of the switching system
• SPC was the enabling technology of electronic switching systems (ESS) developed in the Bell System in the 1950s.
source: Wikipedia
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Inside the Digital Local Exchange
MD
F M
DF
Subscriber Concentrator Unit Subscriber Concentrator Unit Group Switch Unit Group Switch Unit
subscriber line termination unit
subscriber line termination unit
MU
X
MU
X
digital line termination unit (DLTU)
digital line termination unit (DLTU)
subscriber concentrator switch block
subscriber concentrator switch block
exchange control system exchange control system
analog trunk termination unit
analog trunk termination unit
DD
F D
DF
group switch block
group switch block
CAS CAS
CCS CCS
DLTU DLTU
DLTU DLTU
DLTU DLTU
DLTU DLTU
analog trunk
digital trunk
switch block control
switch block control
switch block control
switch block control
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History SPC
• Early exchanges (Strowger and crossbar switches) used analog components (electromechanical switching) without software control
• Invented by Bell Labs scientist Erna Schneider Hoover in 1954
• SPC was introduced in electronic switching systems in the 1960s
• 101ESS PBX was a transitional switching system in the Bell System
• Western Electric 1ESS switch and the AXE telephone exchange by Ericsson were large-scale systems in the public switched telephone network
• SPC enabled sophisticated calling features
• The addition of time-division multiplexing (TDM) decreased subsystem sizes and dramatically increased the capacity of the telephone network
• By the 1980s, SPC technology dominated the telecommunications industry.
source: Wikipedia
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Exchange Control System
• Consists of CPU and Memory, to control relay switch
• CPU could be:
– Distributed Control • Vertical Decomposition
• Horizontal Decomposition
– Centralized Control • Standby Mode
• Synchronous Duplex Mode
• Load Sharing Mode
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CPU Configuration
• Distributed Control, more available and more reliable
– Vertical Decomposition, 1 CPU for 1 block of exchange
– Horizontal Decomposition, 1 CPU performs 1 function
• Centralized Control
– Standby Mode, 1 CPU on + 1 CPU standby
– Synchronous Duplex Mode, 2 CPU on, provide 2 results to compared
– Load Sharing Mode, all CPU on, load is shared in random
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Trunk and Subscriber Line
• Trunk: analog or digital
• Subscriber: analog (PSTN, PBX) or digital (ISDN BRA, PBX PRA)
• Terminating unit should considers: – Varying distance for each subscriber
– Signaling message translation
– Some subscriber still needs ringing current and power feeding
– Features for maintenance and testing
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Subscriber Line Termination Unit
Analog SLTU should provides functionalities:
• Battery feeding (power supply, ex. to CPE) -48VDC
• Over voltage protection (ex. from lightning)
• Ringing current (to bell customer)
• Supervision (to detect CPE condition)
• Coding (encoding and decoding between analog and digital)
• Hybrid transformer (conversion from 2-wire to 4-wire)
• Channel testing
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Subscriber Line Termination Unit
Digital SLTU should provides functionalities:
• Transfer non-voice data
• Use 64 kbps for data transmission
• Use 16 kbps for signaling (CCS)
• Consists of NTU (Network Termination Unit) and TA (Terminal Adapter)
• Supervision is done at TA
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Single Processor vs. Dual Processor
• Availability
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Single Processor vs. Dual Processor
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See you on next class